The function of active medical implants, particularly of implanted medical-electronic device, decisively depends on the availability of a sufficient operating energy. Since these devices often have a permanent, or in case of an emergency, a vital function for the respective patient, sufficient knowledge on the state of the power supply, particularly of the maintenance state of a batter or rechargeable battery of the implant is indispensable.
The currently known methods of evaluating the battery reliability in ICD is suitable to a very limited degree for identifying problems with batteries early, and thus preventing reliability problems of the ICD. Currently, the battery voltages, the minimum battery voltage during a charging process, and the charging times are being utilized as the criteria for battery monitoring.
All of these measurement values are influenced by environmental factors such that a specific analysis of the battery state is possible only in a very limited manner. The charging time is decisively influenced by the forming state of the impact capacitors. The batter voltage depends on the current operating settings of the ICD (with our without stimulation, etc.). An early detection of problems with the battery is therefore not possibly using the methods stated above. In particular, a so-called voltage delay is only detected, if the battery performance is already irreversibly reduced.
A voltage delay is typical particularly in SVO (silver vanadium dioxide) batteries. In order to avoid the same said batteries are reformed in a non-specific manner. This leads to an unnecessary loss of the charge.
The invention is therefore based on the object of providing a method and an arrangement for the reliable and flexible—with regard to the requirements for realization—determination of a substantial state variable of the power supply of an active medical implant, particularly the maintenance state of the battery or rechargeable battery mentioned. In particular, the early detection of problems with the power supply of an implant—in this regard particularly a so-called voltage delay—is enabled by means of the invention.